01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-04-0101 |
| Title of Abstract | Long-Term variability of surface Chlorophyll in the North Indian Ocean: Role of Ocean-Atmosphere Forcings |
| Authors | Pavas Kumar*, Dr. Mangesh Gauns , Dr. Jayu Narvekar |
| Organisation | CSIR-National Institute of Oceanography, Dona Paula, Goa |
| Address | B-7 STAFF QUARTERS, NIO COLONY, DONA PAULA, GOA DONA PAULA, GOA, India Pincode: 403004 E-mail: pavasm86@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | Surface chlorophyll a concentration (Chl-a) in the North Indian Ocean (NIO) exhibits substantial spatial and temporal variability, driven by a complex interplay of oceanic and atmospheric processes. This study investigates the long-term variability in Chl-a across different upwelling and winter cooling regions of the NIO, using satellite-derived Chl-a data spanning from 1997 to 2024, in conjunction with oceanographic and atmospheric reanalysis products. The NIO is divided into five subzones based on coastal upwelling and winter cooling - North Arabian Sea (NAS), South Eastern Arabian Sea (SEAS), Somalia Upwelling Region(SUR), Oman Upwelling Region (OUR), and Sri Lanka Dome Region(SDR). Seasonal and inter-annual variabilities in -a was analyzed in relation to key physical drivers such as sea surface temperature (SST), thermocline depth (D26), upper ocean stratification, wind stress curl, and Ekman pumping velocity. SST exhibits a semi-annual seasonal cycle, peaking in Apr-Jun and Oct⿿Nov, and reaching minima during Jan-Feb and Aug. Long-term (1960-2024) trends indicate a statistically significant warming in SST across all regions, with the most rapid increases observed in SDR (0.0119°C/year) and SEAS (0.0093°C/year), while the lowest SST trend was observed in SUR (0.0051°C/year), followed by OUR(0.0067°C/year). Long-term wind speed showed an overall increasing trend in all the sub domains except in NAS and SEAS. However, post 1997, all regions showed declining trend. Chlorophyll-a concentrations display strong seasonal variability, with maxima during the southwest monsoon (Jun-Sept) and minima during pre-monsoon months (Mar⿿May). From 1997 to 2024, declining trends in chlorophyll-a were observed in NAS, SUR, and OUR, with NAS showing the steepest decline. In contrast, SEAS and SDR showed increasing trends in chlorophyll a, possibly associated with changing monsoonal winds and increasing ocean stratification under a warming climate. These findings enhance our understanding of biophysical coupling and provide insight into the potential impacts of climate variability productivity and economically vital region. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Chlorophyll, North Indian Ocean, Ocean warming, Wind, Upwelling |
| For Awards | yes |
| Date Of Birth | 14-11-2000 |
| ECSN Registration Number | IIOE2-ECSN-0197 |